You seem to forget that it will take a long time for Fuji to have a competitive FF lens lineup. I have no idea if Fuji will bring out FF cameras at some point - I personally hope they keep perfecting the APS-C lineup (bodies and lenses) for awhile longer before getting diluted by a FF effort, but Nikon need be in no hurry to worry about that because it will be a long time before a Fuji FF + lens lineup are competitive together and Nikon would have plenty of time to respond if Fuji did something interesting.

The more interesting question is whether a smaller FF product (like the size of Sony 7r) is something that would sell a lot for Nikon and what tech should Nikon use to deliver it (dSLR vs. mirrorless, F-mount vs. new lens mount, etc...).

Somewhat I disagree with your comments. Fuji came from nowhere to X100 and X100S and then X-T1. I think Nikon is underestimating Fuji here. Although Fuji launched before some SLRs but they were not that popular but looking at X-T1, certainly Nikon should be worried as Fuji is eating up APS-C camera sale.

Do you have sales figures to prove this? Fuji is hardly eating up anything.

Mirror-less is not catching on in North America and Europe Just in Japan really.